Hard to tell

The number and cause of the deaths of migrants is almost impossible to truly calculate due to poor record keeping in third world and autocratic countries, and the cause of their death at borders can't possibly be accurately held up to any reliable number of those that would have died in other circumstances.

Protect the borders

No, I don't think migrants die per year due to increased border barrier meausres, there is a known risk and I think the migrants are aware if they try crossing the atlantic ocean in a wood made vessell that the likely hood of it sinking is great, so they are aware of the risk, it has nothing to do with protecting the borders, its a chance they take.